


Under the Sea

by wellthatjusthappend



Series: Merfolk AU [10]
Category: Batman - All Media Types
Genre: Alternate Universe - Merpeople, Blood and Gore, Disturbing Themes, M/M, Mermay continues!, NO rape, and yes the title is a little mermaid joke, because i can't resist, but disturbing things may be discussed/alluded to, more tags to be added when explicit scenes are added, most of that will be ch2, there are more references later
Language: English
Status: In-Progress
Published: 2019-05-12
Updated: 2019-05-12
Packaged: 2020-03-01 07:41:44
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,849
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18795958
Author URL: https://archiveofourown.org/users/wellthatjusthappend/pseuds/wellthatjusthappend
Summary: “I have been watching you, young detective,” Ra’s voice rang out clearly in the cave, “after much thought, I have decided that you shall be my mate.”Tim’s eyes widened as he realized that Ra’s waswalkingtowards him.“There’s just a few things we need to attend to first.”





	Under the Sea

**Author's Note:**

> I _was_ hoping to have this story be from Jason’s perspective, but I got part way through the first chapter before I had to accept that it just didn’t make sense. Ah, well. 
> 
> Warning: There is violence, disturbing themes, sex, and romance ahead… this is the Mer AU after all.

Tim wished he didn’t have to have a mask every time he went underwater.

He didn’t have many human friends. Not close ones anyway. Most of the friends he did have were Mer or something other like Kon. They had enough land power these days, Tim wished he wasn’t so hopelessly outmatched in the water so he could help fight the good fight under the sea.

The fact that Tim and Jason’s courting had also gotten a lot more serious the last few months… well, that just added to the frustration.

There was so much that he could only sort of be a part of as a human. Bruce and Dick had their own thing and they made it work, mostly by respecting each other’s space and then finding creative solutions when they decided they wanted to spend time with one another. It was probably for the best since they would have probably killed each other a long time ago otherwise. But Tim wanted more than that.

A few weeks ago Jason had asked if, as his potential mate, Tim wanted to help brood with him that year. Tim knew Jason had lost his last nest when he’d been taken from Roman. Even if Jason hadn’t spoken haltingly about the event and some of the implied trauma around it, Tim knew how significant the request was. He wanted to be there with Jason for that, to share that space with him…

He just wasn't sure if he could as a human.

It was one thing to spend a few hours or most of a day with Jason in the water, it was another thing entirely to spend a week or more submerged even if Tim could find mask that would tolerate that kind of thing. Dehydration would be a huge risk and Tim would have to leave every time to eat or go the bathroom. His skin would have to be carefully insulated, not just to prevent hypothermia, but because human skin starts to break down painfully in the water after a day or so and even then he’d be at risk for fungal infections. If that weren’t enough, even shallow submersion for such a long time would change his circulation and muscle stability. It’d take weeks after that kind of thing for Tim to even walk properly again.

He knew what Bruce would say if he knew: no way, not under any circumstances. Even Jason might take back his request if he understood the risks entailed for Tim. But Tim kept on holding out hope that he would think of a solution before the time came. Jason needed him, and Tim wanted desperately to find a way to be there for him.

“Good job… so good… come on Dami, you can catch me…” Tim glanced over as he descended the stairs at in the shallow pool Bruce had constructed (cut off from the rest of the caves) that Dick was swimming in lazily with Damian wriggling determinedly after him. Dick no longer tried to attack outright if Tim got too close, but Damian tended to hiss like some literal little demon out of hell so Tim generally steered clear. He wondered if all Merbabies were like that or just Damian.

Of course, Damian had every right to be a grumpy baby. The little oxygen tank he wore as a backpack interfered with his swimming and he was already unusually clumsy in the water according to Jason (who was quick to criticize how Bruce and Dick were raising the little Mer). He’s also heard Dick fretting a number of times that the breathing mask would slow Damian’s verbal development.

Apparently he should be learning how to chase after small fish at his age, but even if he could swim properly and didn’t have a mask in the way, he still wasn’t really doing solid foods.

“Need any help tonight?” Tim called from a careful distance.

“Nah, we’re good. He’ll be ready for a nap soon enough anyway once he tires himself out a bit more,” Dick said with a small brilliant smile at the growling Merbaby.

Damian had thrown Wayne Manor into quite bit of chaos and Tim wasn’t even sure he liked the kid very much, but Dick had been so happy since his arrival that Tim could never really resent the kid that much.

“Jason and I are going to head out for patrol in a bit, call Alfred if you need anything,” Tim instructed.

“Will Barbara and Steph be out tonight too?” Dick asked, cooing absently as Damian almost caught him.

“Yes, Barbara will be taking the West Side, and Steph will be patrolling the channel,” Tim nodded as he suited up. They were stretched a little thin now that Dick was off patrol for the foreseeable future and Bruce was on a mission for the JLA. Cass had taken over the Bludhaven harbor for Dick, and Steph had started small missions under Barbara’s careful supervision. The Mer had shown marked improvment lately, but still wasn't ready to be out on her own.

“You and Jason?”

“We’re following a lead near the docks. There’s been some shipments of an unusual amount of zebra fish... among other things,” Tim said, fastening his gauntlets on securely.

“Zebra fish, that seems pretty random… oh, you think someone if doing Mer and Human experimentation?” Dick said looking up sharply.

It was an understandably touchy subject in their household.

“Possibly. Their physiology does map to human’s remarkably well despite being a fish so scientists have been known to use them for such projects before. The other chemicals on the shipments… I’m not sure. It doesn’t make a lot of sense, but we have also found some weird codded messages,” Tim said.

“That doesn’t sound good,” Dick frowned.

“Probably not. I was thinking we may try and track down the destination of one of the shipments tonight,” Tim said.

“Alright, take care,” Dick said distractedly as Damian frustrated thrashing caused him to sink. Tim left them to it and made his way to the largest pool that they used for direct passage to the ocean.

Grinning, he unfastened his Robin pin and flicked it into the water. A moment later the water rippled unnaturally and Tim grinned, stepping off the ledge and dropping into the icy water… right into Jason’s arms.

Jason greeted him with a small bite and breath of air that quickly became a dirty kiss as he fastened the Robin pin back onto Tim’s uniform. Tim grinned and pushed him away, jerking his head towards the exit. Jason’s returning smile was just as pleased and dangerous, but he wasted no time in carrying Tim out of the cave.

Diving would technically be more _practical_ for Tim as a human, but… these days he spent every moment he could under the sea.

It didn’t take them as long as Tim thought it would to find one of the suspicious shipments. Jason found a sample of allege on the haul that wasn’t from the area and Tim ran it through his scanner.

“…that’s not too far from here,” Tim noted as he brought up a map of the island the allege came from, a frown creasing his brow, kneeling down to show Jason.

“Can you show be the water version? With the currents and stuff?” Jason asked frowning.

“Sure,” Tim quickly toggled the view. Jason scanned the screen, clumsily adjusting the view before his expression became thunderous, “What?”

“That’s a league base.”

“Are you sure?” Tim blinked in surprise, “We don’t have it on any of our records.”

“It wouldn’t be. But all the Mer know to steer clear of it.”

“… so that means the League of Shadows is most likely the one carrying out the experiments?” Tim said feeling a headache already coming on.

“The sea witch must have restarted her research on hatchlings,” Jason growled, a deep rumbling sound that trailed off into a hiss.

“Charging into a League of Shadows base blind would be suicide,” Tim said sharply, hoping to cut off any plots Jason might be making early.

“So we go scout it out,” Jason insisted.

“ _Can_ you be that close to Talia without a confrontation?” Tim asked skeptically.

“Mer know what stealth is, little bird,” Jason said with a hint of annoyance, “I’m not a hatchling that’s going to sabotage a hunt by getting impatient.”

“Just checking, I know how much you hate her,” Tim raising his hands in surrender. Jason tracked the movement warily and Tim realized he had no idea if the gesture meant something different in Mer culture, “Anyway, I’m not sure if Batman would approve.”

“She must be stopped, the Warrior would want to stop her,” Jason frowned.

“Of course, he just might not like _us_ going alone,” Tim said sighing.

“The rest of the pod is guarding our territory or caring for the hatchling, who else would go?” Jason frowned.

“…Point.”

“You like lots of information for your plans, right? So we must go get you more information,” Jason said nodding to himself.

Tim sighed. He could tell he wasn’t talking Jason out of this one. It was probably a blessing that Jason had told him at all and hadn’t simply gone off on his own.

“Ok, fine, we’ll go,” Tim said, “but we pull back if I say so. We can’t risk… spooking our prey when we’re only just scouting out our hunt.”

“I will follow your lead, little bird,” Jason promised, leaning up to scrape his teeth along Tim’s jaw. Tim shivered, but nipped back warningly.

“Behave,” Tim warned.

“For you? Always,” Jason promised, eyes hooded as he tipped back his head.

It was probably a sign that Tim spent more time with Mer these days than humans that Tim was starting to think that sort of gesture was super hot.

“Good, I’ll get the jet,” he said, quickly looking away from the obvious invitation.

Maybe there would be time to get Jason’s teeth on him somewhere before they arrived at the island.

* * *

 

Tim climbed through the above water caves, keeping an eye out for brooding grooves or any other sign of Mer activity.

Again, he caught himself wishing he could have been born a Mer. This would be so much easier if Tim could be down in the water with Jason, but if they _did_ encounter a Mer… well he could hold his own against one just fine after training with Dick and Jason for so long, but if there were multiple he didn’t stand a chance.

“ _They’re definitely up to something,”_ Jason clicked cover the comm. Tim might not be able to make a lot of the sounds necessary to speak Mermish himself, but he was proficient enough to understand what Jason was saying after almost a year together. It was useful on missions so that Jason didn’t necessarily have to surface every time he wanted to communicate.

“What do you see?” he asked quickly.

“ _A whole lot bio stuff about human and Mer bodies,_ ” Jason replied, “ _There’s a lot of tech too, and they’ve clearly been doing experiments, but no sign of hatchlings yet.”_

“Keep looking, and try to point your mask at anything that looks like it might be important so the camera catches it,” Tim said, hooping down from another boulder. On his wrist feed, he checked Jason’s video. There certainly seemed to be lot of anatomy notes and diagrams… but he would have thought there’d be more about babies, not just adults.

 _Talia, what are you up to?_ Tim frowned.

“Any guards?” he asked.

“ _Not yet, though the witch would want to keep as many outside sources away from the shit she’s doing as possible. Mer don’t take kindly to people messing with hatchlings, even loyal followers,”_ Jason said.

Tim hummed in agreement. Still, something about all of this felt strange. Talia was extraordinarily intelligent, but there was also usually a certain… flare to her activities.

He turned a corner and paused as he noted a slight green glow up ahead.

“Lazarus Pit,” he murmured softly into his comm. He heard Jason curse slightly on the other end.

 _“I’ll head towards you_ ,” Jason said.

“Don’t,” Tim said firmly, “The water is probably contaminated close by. I don’t want you breathing any of that stuff in. Keep gathering information, I’m going to check it out.”

 _“Be careful, little bird,”_ Jason said warningly, “ _Lazarus Pit’s aren’t usually left unguarded.”_

“I’m on land, I should be safe from any Mer guards,” Tim said. “I’ll stop if I have to cross any water.”

Jason made a sound of discontent, but didn’t push.

Tim carefully crawled through the narrow opening from which the glow was coming and into a huge cavern. He blinked in surprise at the intricate carvings, both above and below the water.

He could see a few Mer guards lurking in the shadows of the seawater below him. There was the a short stretch of land, and then a ring of water alight with fire (likely oil on top) and then another stretch of land around a gold inlaid pool of bubbling green water.

This really didn’t look like a base of Talia’s: it was too gaudy. But that meant…

Tim felt the movement behind him just in time to roll to the side out of the way of the sword swinging at him.

 _I didn’t know the League kept human warriors as well as Mer,_ Tim managed to think as he came up on his feet and raised his staff to block the next blow. Another assassin joined the first and Tim had to flip over the roiling water below to avoid them. There was something strange about the way these people moved. Particularly the way they crouched and kicked and leaped as they fought. Tim couldn’t put his finger on why, but the movements came off as distinctly inhuman.

Mer were surfacing in the water all around, and Tim cursed quietly to himself as the two assassins on land tried to drive him into the water.

Instead, Tim moved towards the Pit, even though that was further from his exit.

“Hold,” a commanding voice rang out. All movement instantly stilled.

 _“Little bird, what’s going on?”_ Jason’s voice came urgently through the comm.

“Ra’s,” Tim said, as both greeting and reply. He heard Jason hiss quietly in alarm.

“Hello Timothy,” Ra’s said mildly as he reclined in the green water. He must have been underneath the surface when Tim arrived, he realized.

“I didn’t realize this was _your_ establishment. I was just checking out some unusual activity in the area,” Tim said lightly, “If you don’t mind, I’ll be going now.”

“Oh but I _do_ mind, young detective,” Ra’s said, “you were very clever to figure out about this place’s existence at all, but really I had been hoping you would.”

“Really? And why’s that?” Tim said, carefully edging towards the exit as warning bells went off in his head.

 _This was a set up._ But for what, Tim wasn’t sure. One thing was for certain, he needed to keep Ra’s talking. As subtly as he could, he triggered the panic button on his side that would alert the Cave to his whereabouts. Hopefully Jason wouldn’t do anything reckless in the meantime.

“I have been watching you, young detective,” Ra’s announced as he raised himself out of the pool… and kept rising.

Tim’s first thought was, _that’s a very naked naked man_. And his second was, _fuck, he has legs._

“You… this is what you’ve been working on,” Tim breathed, his mind flashing to experiments Jason had discovered in the caves below.

“Why be limited to only land or water? Surely someone like you understands the frustrations of that, young detective,” Ra’s said still advancing towards him.

“Why were you hoping _I_ would come? I thought your obsession was with Bruce,” Tim said warily as an attendant hurried forward to give Ra’s a robe and a sword.

“Well you see, after much thought, I have decided that you shall be my mate.”

“ _What?”_ The world seemed to freeze for a moment and Tim’s eyes widened in alarm as Ra’s continued to advance on him.

“The Detective proved too inflexible, his human ‘code’ bringing him nothing but weakness,” Ra’s said regretfully, “But you, I’ve seen you with that unworthy brat of a Mer. You have everything the Detective lacks. You’re going to be _perfect.”_

Tim needed to get out of there _now_.

“I’m not interested,” Tim said, raising his staff.

“You will be,” Ra’s promised, nodding to one of the assassins behind Tim. Whirling around, Tim just managed to block the next several attacks. He stumbled back slightly against the inhuman force behind the strikes and came up against a bare chest. By the time Tim realized his mistake, it was too late.

“There’s just a few things we need to attend to first,” Ra’s murmured in his ear.

Tim watched in detached horror as Ra’s sword pierced his armor and his stomach. Then the pain and shock set in and his world went black.

 

**Author's Note:**

> Considering everything outlined about Mer culture thus far, it’s probably not all that surprising that’s Ra’s creepy obsession with Tim has taken this shape. Can you guess where this is going?


End file.
